The present invention relates generally to an apparatus and method of attaching and aligning an optical targeting or alignment system to a base. More particularly, this invention pertains to an apparatus and method of attaching and aligning optical sighting systems to a ballistic launcher. Even more particularly, this invention pertains to an adjustable mounting system for a telescopic scope.
It is long known in the art to provide mechanical means for adjusting the elevation of sighting and ranging devices mounted to a base. Aiming or sighting devices, laser target illumination devices and laser ranging devices are commonly mounted to ballistic projectile launchers, such as rifles, to survey equipment, and to other apparatus requiring alignment along a longitudinal axis. Common aiming or sighting devices include various types of telescopic optical scopes. Other aiming or sighting devices include telescopic and non-telescopic thermal imaging scopes and telescopic and non-telescopic amplified light imaging optical scopes.
Adjustable mounting systems are frequently used to mount telescopic scopes, and other similar aiming devices, upon barrels of rifles or other similar firearms. The most common telescopic scopes are non-amplified, optical telescopic scopes having front and rear mounting points. Such a telescopic scope is attached by means of a mounting system to the barrel of a rifle in a configuration having the rear sight of the scope adjacent to the rifle's breach and the front sight of the scope directed toward the muzzle of the rifle. The scope's sighting axis is approximately aligned with the bore axis of the rifle and is adjusted vertically in elevation and adjusted laterally in windage such that the point of aim observed by the shooter is the point of impact of the projectile at the desired range. Other elevation and windage adjustments may be necessary based on number of well known factors including wind speed and direction, temperature, humidity, projectile shape and mass, and powder mass and burn characteristics. Since projectiles follow a ballistic path, adjustments of elevation may be a critical factor for hitting targets at ranges approaching the maximum range of the cartridge-rifle combination.
The range in elevation adjustments needed for telescopic scopes mounted to high powered sporting and military rifles frequently exceeds the range in elevation adjustments achievable by elevation and windage adjustment mechanisms incorporated within the telescopic scope itself. These internal adjustment mechanisms of most telescopic scopes are less accurate over the outer portion of their adjustment ranges. The internal adjustment mechanisms frequently are positioned such that a shooter in the firing position cannot easily reach the internal adjustment mechanisms and cannot readily read the adjustment markings. Additionally, the internal adjustment mechanisms of telescopic scopes may be inadvertently displaced by acceleration experienced during recoil and other shocks.
Adjustable mounting systems are used to mount telescopic scopes so as to provide for larger ranges of elevation adjustment and greater resistance to displacement of the elevation adjustment mechanism during recoil or other shocks. One such adjustable telescopic scope mounting system is shown in FIGS. 1 and 3. This mounting system (herein referred to as the “Ivey 50 MOA” mounting system) was developed by Stephen Ivey and manufactured by Ivey Design of Murfreesboro, Tenn. The Ivey 50 MOA mounting system is adjustable within 1.0 m.o.a. (minute-of-arc) graduations between 0 m.o.a. and 50.0 m.o.a.
The Ivey 50 MOA mounting system includes an adjustable elevation mount 14 as the front mount and a pivoting mount 12 as the rear mount. The adjustable elevation mount 14 includes an adjustable sub-base 26 and the pivoting mount 12 includes a fixed sub-base 28. Each sub-base 26, 28 and corresponding base clamp 48, 50 are positioned upon the base rail 56 and are fixedly held in position by rail clamp bolts 52 positioned through each sub-base 26, 28 and corresponding base clamp 48, 50 and fastened with rail clam nuts 54. The base rail 56 is in turn rigidly attached to the rifle barrel or action. The Ivey 50 MOA mounting system may be adapted to fit various types of bases, including flat bases, dovetail bases and Picantinny bases among others.
The pivoting and adjustable mounts 12, 14 each include an upper assembly, commonly referred to as scope rings, having support bearings with an internal diameter approximately the same as the diameter of the telescopic scope at its mounting points. These scope rings each include an upper ring cap 20 that is fastened to the lower ring portion 22 by ring bolts so as to rigidly hold the telescopic scope to the support bearings. The lower portion 22 of each scope ring further includes a clevis 23 portion forming a clevis opening adapted to receive a portion of a sub-base 26, 28. For each scope ring, the lower ring portion 22 and the sub-base 26, 28 are bolted to form a clevis connection. The adjustable elevation mount 14 and a pivoting mount 12 form a rigid assembly when holding a telescopic scope.
The pivoting mount 12 of the Ivey 50 MOA mounting system is proximate the rear sight of the telescopic scope when a scope is mounted on a rifle. The lower ring portion 22 of this mount has two clevis pivot holes 106 that are aligned with the base pivot hole 107 of the fixed sub-base 28. These holes form a through hole that is closely sized in diameter to the diameter of a pivot pin bolt 30 extending through these holes and fastened with a nut. This type of clevis connection allows the scope ring of the pivoting mount 12 to pivot around the pivoting mount 12 upon loosening of the clevis connection.
The adjustable elevation mount 14 is proximate the front sight of the telescopic scope. The lower ring portion 22 of this mount has two clevis pivot holes 106 that are aligned with the vertical slot 108 (not shown in FIG. 1, but as shown in FIG. 4) of the adjustable sub-base 26. Referring again to FIG. 1, an elevation pin 31 extends through the clevis pivot holes 106 and the vertical slot 108 and is fastened with a nut. This clevis connection allows the scope ring of the adjustable elevation mount 14 to travel along a vertical direction shown by arrow 104 upon loosening of the clevis connection.
The adjustable elevation mount 14 includes a cylindrical bore disposed longitudinally through the adjustable sub-base 26 and having a first internally threaded opening receiving a locking setscrew 42. A second internally threaded opening receives an externally threaded barrel 40. The barrel has an internally threaded barrel bore that receives a threaded and extending portion of a micrometer head 39. The locking setscrew 42 and the extending portion of the micrometer head 39 are disposed in opposition.
An elevation cam 36 is slidably disposed in the cylindrical bore between the locking setscrew 42 and the extending portion of the micrometer head 39. The elevation cam 36 has a cylindrical body with flat faced ends and an angled slot 110 cut laterally through the cylindrical body. The angled slot 110 receives the elevation pin 31 as it extends through the vertical slot 108 of the adjustable sub-base 26. The locking setscrew 42 and the extending portion of the micrometer head 39 are each in contact with but not affixed to a flat faced end of the elevation cam 36. Adjustments of the locking setscrew 42 and the micrometer head 39 position the elevation cam 36 along a longitudinal direction of travel shown by arrow 102. The angled slot 110 is adapted to provide a track for forcing the elevation pin 31 to travel vertically when the elevation cam 36 is moved past the elevation pin 31, thus lowering and lifting the sight ring of the adjustable elevation mount 14.
Elevation adjustment of the Ivey 50 MOA mounting system is accomplished by using hex key wrenches to loosen the pivot pin 30 and the elevation pin 31 fixing nuts connecting the scope rings to the sub-bases 26, 29 on the pivoting and adjustable mounts 12, 14, respectively. A hex key wrench is then used to loosen the locking setscrew 42 butted to the rear of the elevation cam 36 so as to allow travel of the elevation cam 36. The micrometer head 39 is adjusted to a new, selected position. The locking setscrew 42 is retightened against one face of the elevation cam 36 so as to reposition the elevation cam 36 in firm contact against the opposing the micrometer head 39. Finally the pivot pin 30 and the elevation pin 31 are retightened using hex key wrenches.
The Ivey 50 MOA mounting system and other prior art systems have several disadvantages when used in demanding environments. First, elevation adjusting dials of many are exposed. For the Ivey 50 MOA mounting system the micrometer head extends in front of the mounting system and the corresponding elevation adjusting dials of other prior art systems extend laterally from their mounting systems. When hunting in rough terrain, obstacles may strike these exposed elevation adjusting dials and cause movement and misadjustment of the elevation adjustment set in the mounting system. Loss of an external tool would render the adjustment mechanisms unusable until such time as a new tool can be procured. Use of external tools, such as hex wrenches, is disadvantageous when it is necessary to make an elevation adjustment quickly, quietly and with a minimum of motion. Finally, when a shooter is in the shooting position it is very difficult to make an elevation adjustment to the mounting system without movement out to the shooting position.
The Ivey 50 MOA mounting system is susceptible to interrupted or incorrect positioning of the elevation cam 36 if either the locking setscrew 42 or the micrometer head extending portion 39 do not fully and firmly contact the elevation cam 36. Oil, dirt or debris may create an physical offset between a flat face of the elevation cam 36 and either of these positioning means. Such an offset causes small variations in vertical travel of the scope ring of the adjustable elevation mount 14 and, thus, causes a reduction in the smoothness, accuracy and precision of the elevation adjustment.
What is needed, then, is an adjustable mounting system for a telescopic scope that provides an elevation adjustment dial adapted to be used while the shooter is in the shooting position, that provides a means for making elevation adjustments quickly, quietly and with a minimum of motion, that provides a means for making elevation adjustment without the use of external tools (tool-less elevation adjustments) and provides an elevation adjustment dial that is protected from obstacles.
Additionally, what is needed is an adjustable mounting system for a telescopic scope that provides for smooth, accurate and precise transmission of bi-directional travel of the elevation cam mechanism within the bore of the adjustable sub-base and so as to prevent oil, dirt or debris from distorting the positioning of the elevation cam mechanism by the elevation adjustment dial.